Help SMC Pentax 1:1.2/50

Prince Harbinger · 03-22-2021, 08:30 PM

Hey, guys just picked up my first SMC Pentax F/1.2 50mm PK. It has a fungus infestation. I cleaned the worst of it off. The glass looks flawless. However, I need help getting to the rear element. I'm not sure what to expect unscrewing any of the screws from the mount, or the top where the aperture blades rest. There's no need to clean the blades as they are not oily. The focusing is very smooth. I'd like to just get under the rear element and clean the remaining bit of fungus. Can someone with experience in cleaning this lens guide me through it?

Here's some photos.

Dropbox - 20210322_205807.jpg - Simplify your life

Dropbox - 20210322_222555.jpg - Simplify your life

Dropbox - 20210322_222627.jpg - Simplify your life

Dropbox - 20210322_223140.jpg - Simplify your life

Dropbox - 20210322_222831.jpg - Simplify your life

krazykat · 03-22-2021, 10:18 PM - **1 Like**

Just looking at the fourth photo, it looks like you might have some element separation in the cemented doublet.

Oh, hopefully this helps too:
https://www.pentaxforums.com/forums/114-maintenance-repair-articles/278469-p...mbly-pics.html

Prince Harbinger · 03-23-2021, 12:19 AM

Originally posted by krazykat

Just looking at the fourth photo, it looks like you might have some element separation in the cemented doublet.

Oh, hopefully this helps too:
Pentax K 1.2/50mm Disassembly pics - PentaxForums.com

Looks like fungus to me. I don't see any rainbows. I looked at sample photos of separation and it doesn't look like what my lens has. I saw that thread. What they didn't show is how to remove the cemented elements. I'm assuming once you remove the lens mount you can just unscrew the rear optic from the block?

krazykat · 03-23-2021, 04:29 PM - **1 Like**

I hope you're correct and that it is just fungus.👍

I don't have any experience with this particular lens, but with other K lenses I've looked at you just take off the mount and then unscrew pieces one by one using a lens spanner or just your fingers. The trickiest bit I find is keeping the aperure mechanism intact and the spring attached.

Prince Harbinger · 03-23-2021, 06:22 PM

Originally posted by krazykat

I hope you're correct and that it is just fungus.👍

I don't have any experience with this particular lens, but with other K lenses I've looked at you just take off the mount and then unscrew pieces one by one using a lens spanner or just your fingers. The trickiest bit I find is keeping the aperure mechanism intact and the spring attached.

Not sure but it's not easy to see you have to angle the flashlight just right to notice it. You won't see it without the flashlight. Someone told me it appears mild and shouldn't affect the image quality. I'm sure it could likely be cleaned off. How can I prevent it from getting worse? I'm thinking about picking up a near mint backup copy.

Here's another photo.

Dropbox - 20210323_162159.jpg - Simplify your life

restoration of the rear elements housing.

Before
Dropbox - 20210323_125104.jpg - Simplify your life

after
Dropbox - 20210323_141301.jpg - Simplify your life

Prince Harbinger · 03-23-2021, 08:54 PM - **1 Like**

Update all done.

Before
Dropbox - 20210322_205807.jpg - Simplify your life

Dropbox - 20210322_205845.jpg - Simplify your life

after

Dropbox - 20210323_233840.jpg - Simplify your life

Dropbox - 20210323_234010.jpg - Simplify your life

Dropbox - 20210323_234223-01.jpeg - Simplify your life

krazykat · 03-23-2021, 10:27 PM - **1 Like**

Nice. Looking really good!

03-22-2021, 08:30 PM	#1
Prince Harbinger Veteran Member Join Date: Jul 2018 Location: New Jersey Posts: 429	Help SMC Pentax 1:1.2/50 Hey, guys just picked up my first SMC Pentax F/1.2 50mm PK. It has a fungus infestation. I cleaned the worst of it off. The glass looks flawless. However, I need help getting to the rear element. I'm not sure what to expect unscrewing any of the screws from the mount, or the top where the aperture blades rest. There's no need to clean the blades as they are not oily. The focusing is very smooth. I'd like to just get under the rear element and clean the remaining bit of fungus. Can someone with experience in cleaning this lens guide me through it? Here's some photos. Dropbox - 20210322_205807.jpg - Simplify your life Dropbox - 20210322_222555.jpg - Simplify your life Dropbox - 20210322_222627.jpg - Simplify your life Dropbox - 20210322_223140.jpg - Simplify your life Dropbox - 20210322_222831.jpg - Simplify your life

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03-22-2021, 10:18 PM - 1 Like	#2
krazykat Veteran Member Join Date: Aug 2010 Posts: 546	Just looking at the fourth photo, it looks like you might have some element separation in the cemented doublet. Oh, hopefully this helps too: https://www.pentaxforums.com/forums/114-maintenance-repair-articles/278469-p...mbly-pics.html

03-23-2021, 12:19 AM	#3
Prince Harbinger Veteran Member Join Date: Jul 2018 Location: New Jersey Posts: 429 Original Poster	Originally posted by krazykat Just looking at the fourth photo, it looks like you might have some element separation in the cemented doublet. Oh, hopefully this helps too: Pentax K 1.2/50mm Disassembly pics - PentaxForums.com Looks like fungus to me. I don't see any rainbows. I looked at sample photos of separation and it doesn't look like what my lens has. I saw that thread. What they didn't show is how to remove the cemented elements. I'm assuming once you remove the lens mount you can just unscrew the rear optic from the block?

03-23-2021, 04:29 PM - 1 Like	#4
krazykat Veteran Member Join Date: Aug 2010 Posts: 546	I hope you're correct and that it is just fungus.👍 I don't have any experience with this particular lens, but with other K lenses I've looked at you just take off the mount and then unscrew pieces one by one using a lens spanner or just your fingers. The trickiest bit I find is keeping the aperure mechanism intact and the spring attached.

03-23-2021, 06:22 PM	#5
Prince Harbinger Veteran Member Join Date: Jul 2018 Location: New Jersey Posts: 429 Original Poster	Originally posted by krazykat I hope you're correct and that it is just fungus.👍 I don't have any experience with this particular lens, but with other K lenses I've looked at you just take off the mount and then unscrew pieces one by one using a lens spanner or just your fingers. The trickiest bit I find is keeping the aperure mechanism intact and the spring attached. Not sure but it's not easy to see you have to angle the flashlight just right to notice it. You won't see it without the flashlight. Someone told me it appears mild and shouldn't affect the image quality. I'm sure it could likely be cleaned off. How can I prevent it from getting worse? I'm thinking about picking up a near mint backup copy. Here's another photo. Dropbox - 20210323_162159.jpg - Simplify your life restoration of the rear elements housing. Before Dropbox - 20210323_125104.jpg - Simplify your life after Dropbox - 20210323_141301.jpg - Simplify your life

03-23-2021, 08:54 PM - 1 Like	#6
Prince Harbinger Veteran Member Join Date: Jul 2018 Location: New Jersey Posts: 429 Original Poster	Update all done. Before Dropbox - 20210322_205807.jpg - Simplify your life Dropbox - 20210322_205845.jpg - Simplify your life after Dropbox - 20210323_233840.jpg - Simplify your life Dropbox - 20210323_234010.jpg - Simplify your life Dropbox - 20210323_234223-01.jpeg - Simplify your life

03-23-2021, 10:27 PM - 1 Like	#7
krazykat Veteran Member Join Date: Aug 2010 Posts: 546	Nice. Looking really good!